module.exports = app => {
    const { STRING, INTEGER } = app.Sequelize
    const Chapter = app.model.define("chapter", {
        title: STRING,
        orderby: INTEGER
    })
    Chapter.associate = function() {
        app.model.Chapter.belongsTo(app.model.Book, {
            foreignKey: 'book_id',
            as: 'book'
        })
    }
    return Chapter
}